1. Field of the Invention
The present invention relates generally to the field of burners for the combustion of fuel-air mixtures such as are utilized in a wide variety of industrial applications. Specifically, the invention is addressed to that type of burner wherein air is supplied to a combustion zone after having a rotary, swirling motion imparted thereto so as to provide turbulence for the mixing of fuel and air, thereby effecting intense and efficient combustion.
In burners of this type, it is often desirable that the burner be designed so as to operate over a fairly wide range of required heat output. In doing so, however, it is necessary that suitable combustion air flow control means be provided so as to maintain effectiveness of the rotary, swirling motion imparted to the air at reduced flow rates. The present invention provides a means for effectively varying the capacity of such a burner between a maximum rated value and a value equal to as low as 10% of its rated capacity.
2. Description of the Prior Art
U.S. Pat. No. 1,341,524 discloses a hydrocarbon burner wherein a circular array of air directing vanes acts upon combustion air prior to its admission to a combustion zone and wherein a movable shutter 60 is provided for varying the amount of air passing through said vanes. Shutter 60 comprises a circular, planar member disposed entirely inside the array of air turning vanes, which vanes have inner edge portions lying parallel to the direction in which shutter 60 reciprocates.
U.S. Pat. No. 2,757,721 discloses a second burner assembly which includes a circular array of air directing vanes wherein a desired flame pattern may be produced by selectively positioning a cylindrical baffle 61 which surrounds the array and a generally circular baffle 48 which lies at the interior of said array.
U.S. Pat. No. 1,329,279 discloses a burner assembly also having a circular array of air directing vanes wherein the entire vane assembly is movable with respect to a stationary shroud encircling said array, whereby the volume of air flowing through the vanes to a combustion zone may be varied.